Process of and apparatus for separating coal from coal culm



R. N. NOLL June 19, 1934.

PROCESS OF AND APPARATUS FOR SEPARATING COAL FROM COAL CULM Filed 001;.27, 1931 2 Sheets-Sheet l gnuenfoz dam R. N. NOLL June 19, 1934.

PROCESS OF AND APPARATUS FOR SEPARATING COAL FROM COAL CULM Filed Oct.27, 1931 2 Sheets-Sheet 2 Jnwnfot R-IV- IVoZZ damn,

Patented June 19, 1934 UNITED STATES PATENT OFFICE mocnss or ANDAPPARATUS FOR SEPA- RATING coAr. mom com, com

Rosa Nelson Noll, Philadelphia, Pa., assignor of one-fourth to MichaelAngelo Sciullo, Vineland, N. J.

Application October 27, 1931, Serial No. 571,391

3 Claims. (01. 209-173) coal and slate into a tank of liquid, the coalfloating upon the surface of the liquid and being carried off from thestone or slate which sinks to the bottom of the liquid.

The general object of the invention is to provide a new method ofseparation which includes the discharge'of the coal from the culm heapinto a. flotation medium consisting of a mixture of sulphuric acid andmagnesium sulphate, to thereby 'secure a medium of higher density thanof sulphuric acid alone and further securing a reduction in the acidityof the resulting solution by virtue of the common ion effect.

A further advantage of the use of this medium resides in the fact thatsuch increase in density brings about a cleaner separation of the culmby reason of the fact that the intermediate densities will all rise tothe surface and not be merely suspended within the liquid or distributedtherethrough.

A further object is to provide an apparatus whereby this process may becarried out which provides for the use of soft rubber rolls whereby theexcess water may be squeezed from the raw culm to thus permit the culmto be used without regard to the water content thereof and to dischargethis damped or dry culm to the separating tank, the separating tankcontaining a medium consisting of a solution of sulphuric acid, togetherwith magnesium sulphate, the worthless impurities being allowed to sinkwhile the floating coal is carried to a discharge chute.

A further object is to provide means whereby the cleaned coal from theseparating tank is passed through rollers to thus free the coal ofexcess medium and the salvaging of this medium so squeezed out of thiscoal.

Other objects will appear in the course of the following description.

My invention is illustrated .in the accompanying drawings, wherein:

Figure 1 is a vertical section through the apparatus;

Figure 2 is a top plan view thereof;

Figure 3 is a vertical sectional view through the elevating worm fordischarging the impurities from the settling tank.

Referring to these drawings, 10 designates the settling tank which ispreferably hopper-shaped and may be lined with hard rubber, pitch orlike material designated 11. The upper end of the settling tank is openand disposed above this upper end is an endless chain or equivalentelement designated 12 having the paddles 13. This endless conveyorpasses over the rollers 14 mounted at opposite ends of the tank anddriven by any suitable means not shown.

The lower flight of this endless belt or like member is slack and movesthrough the liquid within the settling tank. The purpose of this endlesselement 12 is to cause the floating coal to travel from one end portionof the tank where it enters to the discharge end of the tank.

The coal from the culm pile is discharged upon the chute 15 which inturn discharges the coal upon an endless belt or conveyor 16 of anysuitable length and of any suitable material. This passes around therollers 17 and 18 driven in any suitable manner. Above the roller 1'7there is disposed the roller 19 in relatively close contiguity to thebelt. These rollers 17 and 19 are preferably made of soft rubber. Thiscauses the culm to be squeezed and frees it from any excess moisture.The coal after it passes between the rollers 1'7 and 19 is discharged onto a downwardly directed chute 20 which also acts as a scraper operatingagainst the belt 16 and this chute 20 discharges the dry or partiallydry coal into the separating or flotation tank 10. Thistank is filledwith a solution of sulphuric acid to which magnesium sulphate has beenadded for the reason which will be hereafter stated.

In the separating tank, the coal floats while the worthless impuritiessink to the bottom of the tank. The floating coal is carried by thepaddles 13 to the chute 21 and is discharged to the endless belt 22passing over the rollers 23 and 24 and driven in any suitable manner.Immediately above the roller 24 is disposed a roller 25. One or both ofthese rollers are of hard rubber and here again the moisture or excessmedium is squeezed out of this fine coal, thus freeing the coal from theexcess medium, that is, from the sulphuric acid.

The coal passes to the chute 26 where it is sprayed with water by meansof a spray pipe 27 which cleans the coal of any medium which. mightstill adhere to it and likewise forces the coal down the chute into acoal car or any othersuitable receptacle. The medium which has beensqueezed out of this coal is caught in a hopper 28 disposed beneath thechute 21 and the endless belt 22 and the rollers 24 and'from thishopper, the acid medium is carried by the pipe 29 to a reserve tank 30.The pipe 29 is .preferably cast iron and the reserve tank is preferablymade of spiral conveyor v34 operating within the casing 35. This tubularcasing extends upward to any desired height and at its upper end isformed with a discharge opening 36 discharging on to a chute 37. Thechute 37 discharges on to an endless belt 38 supported by the rollers 39and 40 and above the roller 40 there is disposed a roller 41. Therollers 40 and 41 are preferably made of hard rubber or like materialand they act to squeeze the liquid medium out of the fine stone orslate. This worthless residue after passing between the rollers 40 and41 is discharged on to the discharge chute 42, the upper end of thisdischarge chute 43 acting to scrape the surface of the belt 38 and thusremove all residue therefrom. The same function is performed by theupwardly extending end of the chute 26 previously referred to.Immediately below the endless belt 38 is disposed the hopper 44 whichdischarges into a pipe 45 in turn discharging the squeezed out acid ormedium into the reserve tank 30 from which as before stated it is pumpedupward into the main tank.

It will be understood that the contents of the reserve tank are emptiedfrom time to time by means of the pump 32 which is preferably made ofmanganese steel. The pump 32 does not act continuously. The screw 34with its housing 35 is also made of cast iron or manganese steel.

The reason for using a medium consisting of a solution of sulphuricacid, together with magnesium sulphate is as follows:Inasmuch as thedensity of coal ranges from 1.38 to 1.40 while the density of slateranges from 1.8 to 1.9, it is obvious that the former could be separatedfrom the latter .by selecting a medium such that its density would rangebetween these two densities. The medium used is sulphuric acid but puresulphuric acid in commercial work is 1.8400. This is rather too high indensity to use in this process. The correct condensation, however, maybe found by considering it as a problem in direct proportion. Theequation will read:The desired density: 1.8400 as a unit volume: X whereX is the volume that the strong acid has to be diluted to in order toobtain the desired density. By a series of experiments, the mostefficient density was found to be 1.7000. In this medium, the culm ispoured in and mixed. The coal immediately rises to the surface of themedium and may be collected in any suitable manner.

It is desirable, however, to raise the density of the sulphuric acid andto this end, a suitable salt such as magnesium sulphate is added to theacid. This causes the density of the sulphuric acid to rise when thesalt is dissolved. By raising the density of the sulphuric acid by theuse of magnesium sulphate, a safer medium is secured in that the acidityof the resulting solution is decreased and second, because of the risein density, a cleaner separation of the culm is brought about by reasonof the fact that particles of intermediate densities will all rise tothe surface and not be merely distributed throughout or suspended in theliquid.

By a series of experiments, it was found that the desired density liesbetween 1.50 and 1.70

depending upon the type of culm being separated-and the desired volumemaybe foundby using the equation heretofore stated. In order to securethe desired density, it is necessary that the acid be diluted with purewater and since the water so used has the magnesium sulphate dissolvedtherein, the dilutent itself has a density. Therefore, in order toobtain the final volume, take the density of the aqueous solution: 1(density of water) X V, where V is the volume that the acid-has tobediluted to in order to obtain the desired gravity using watercontaining magnesium sulphate as the dilutent. By

saving-the medium, the process can be put on a very economical basis. Inactual practice, almost 50% of the medium is saved which would otherwisebe lost.

By mixing a small amount of magnesium sulphate in a volume of sulphuricacid, the density of the acid will be raised in proportion to the amountof added salt. Now thishas a. decided advantage over the use of the acidalone, since the medium can be made to have a very high density, thuseffecting a much cleaner separation. Secondly, when any salt, as forinstance, sulphate of magnesium is mixed with sulphuric acid, theresulting solution is far less corrosive than the pure acid. Thus thereis produced an excellent medium and at the same time the danger of usingit is decreased.

Furthermore, it is a well-known fact that ma nesium and zinc salts havethe ability to resist dust when deposited on materials. Thus when culmis separated, the individual coal particles will have a certain dustresisting power. Furthermore, the addition of salt to the acid will meana less amount of acid to be used and thus there is a distinct saving ofthe amount of acid needed in the process. Magnesium or zinc salts aresuificiently cheap to warrant such procedure. 1 While I have beforereferred to and prefer to use magnesium sulphate; other salts may beused such, for instance, as sulphate ofzinc, sulphates 'of sodium,potassium or copper.

. While I have described and illustrated what I regard as a veryeffective mechanism for carrying out my process, I do not wish to belimited to the exact details shown, as obviously these might be modifiedin many ways without departing from the spirit of the invention, asdefined in the appended claims. Thus the rolls 17 and 19, 24 and 25 and40 and 41 may be of any suitable material which will force the water oracidified water from the culm or from the cleaned coal or refuse. By theuse of soft rubber, the no water will be effectively squeezed out of thecoal or culm.

I claim:

1. In a process for separating coal in culm from the worthless residueof the culm, the step 135 of discharging the culm into a body ofsulphuric acid diluted with a solution of metallic sulphate.

2. A process for separating the coal in culm from the worthless residueconsisting in pressing out the water in the culm, discharging the culminto a body of liquid having a density lying between 1.50 and 1.70,removing the floating coal from the surface of the liquid, submittingthe coal so removed to pressure to discharge the liquid therefrom,removing the residue from the 1 liquid, and pressing this residue todischarge liquid therefrom.

3. An apparatus for separating coal in culm from worthless residuecomprising a tank for containing a suspension liquid, the tank havingthe form of a hopper, a conveyor discharging the culm into the top ofthe tank and having in its length liquid expressing rollers of softrubber between which the culm passes, means disposed above the top ofthe tank for causing the coal suspended in the upper portion of theliquid to pass from the inlet end of the tank to the discharge endthereof, a second conveyor on to which the coal is discharged, liquidexpressing rollers of soft rubber mounted in connection with the secondnamed conveyor and between which the coal passes, a collecting tank,means for carrying the liquid expressed from the coal to said collectingtank, means in the lower portion of the hopper for conveying theworthless residue from the lower portion of the liquid out of the tank,means for expressing liquid from this worthless residue and dischargingthe residue comprising a pair of coacting soft rubber rollers, means forcarrying said liquid to said collecting tank, and means whereby theliquid from'the collecting tank may be discharged back into the maintank.

ROSS NELSON NOLL.

